The objective of this invention is to improve on the construction of standing T-rib metal roofs in two important respects not heretofore known or utilized in the prior art.
In the past, where the roof area to be covered is of such size that each roof panel must be formed of plural sections which require lapping and joining endwise, difficulties are experienced, and the quality and appearance of the finished roof is adversely effected. The channel-like roof panels to be joined or lapped endwise require cutting and fitting on the job site in a rather haphazard and non-uniform manner, and the quality of the resulting joint or splice will depend largely on the skill of the particular roofer and varies from satisfactory to poor. Also much additional labor time is required.
By means of the present invention, this entire prior art problem is overcome in a very economical manner and a roof of superior quality and appearance can always be achieved without the need for highly skilled workers. Essentially, under the invention one end of each roof panel section to be joined telescopically and longitudinally with another panel section is smoothly tapered so that its cross sectional thickness is reduced sufficiently for entry lengthwise into the untapered end portion of another like roof panel section. The taper extends over a substantial portion of the length of the panel so as to be substantially unnoticeable to the eye of an observer, thus providing a smooth joint. No cutting, crimping or bending of metal on the job site is necessary, and the resulting joint or splice is perfectly smooth. Consequently, the finished roof is smooth and free of buckling or other like imperfections which have occurred in the prior art.
The second major feature of improvement embodied in the invention resides in the provision of an improved roof panel attaching or mounting clip which is concealed in the final roof assembly and which assures better lateral alignment of adjacent panels at a uniform height above supporting purlins. The clip provides a stand-off space between the bottoms of roof panels and the purlins, which space can receive an insulation blanket while simultaneously allowing better access to the heads of fasteners which secure the clips to the purlins. The vertical stand-off space lifts the metal roof off the metal purlins or other metal support structure and thereby reduces thermal conductivity in an area which has always presented a problem to the metal roof area. In actual experience in snow-load conditions on metal roofs the line of metal purlins can be visibly recognized because heat is conducted through the metal roof at the purlin area and the snow is melted over the purlin line. This visibly demonstrates the great heat loss in spite of insulation at the purlin area. By introducing a vertical stand-off this second major feature greatly increase the value of a metal roof with regard to thermal efficiency.